mainwindow: do not call activateWindow on Wayland

It's not supported by wayland and will stop the app

Gitlab: #515
Change-Id: I9f23b781243ec6b85e81121851a531c7e09721b9

src/mainwindow.cpp

@@ -253,7 +253,10 @@ void MainWindow::showWindow()
     } else {
         showNormal();
     }
+
+    if (QGuiApplication::platformName() != "wayland") {
         activateWindow();
+    }
     raise();
 }